Medical mycologyis the study of mycoses of man and their etiologic agents.Mycosesarethe diseases caused by fungi. Of the several thousands of speciesof fungi that are known, lessthan100are pathogenic to man.

In addition to those species whichare generally recognized aspathogenic to man it is firmlyestablished that under unusualcircumstances of abnormalsusceptibilityof patient, or thetraumatic implantationof thefungus, other fungi are capable of causing lesions.Those are called(Opportunistic Fungi.)